The patch adds a new OVS action, OVS_ACTION_ATTR_TRUNC, in order to
truncate packets. A 'max_len' is added for setting up the maximum
packet size, and a 'cutlen' field is to record the number of bytes
to trim the packet when the packet is outputting to a port, or when
the packet is sent to userspace.
Signed-off-by: William Tu <u9012...@gmail.com>
---
include/uapi/linux/openvswitch.h | 7 +++++++
net/openvswitch/actions.c | 28 +++++++++++++++++++++++++++-
net/openvswitch/datapath.c | 9 +++++++--
net/openvswitch/datapath.h | 2 ++
net/openvswitch/flow_netlink.c | 9 +++++++++
net/openvswitch/vport.c | 1 +
6 files changed, 53 insertions(+), 3 deletions(-)
diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index bb0d515..6d7ac5b 100644
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -580,6 +580,11 @@ enum ovs_userspace_attr {
#define OVS_USERSPACE_ATTR_MAX (__OVS_USERSPACE_ATTR_MAX - 1)
+struct ovs_action_trunc {
+ uint32_t max_len; /* Max packet size in bytes. */
+};
+#define ETH_MIN_FRAME_LEN 60
+
/**
* struct ovs_action_push_mpls - %OVS_ACTION_ATTR_PUSH_MPLS action argument.
* @mpls_lse: MPLS label stack entry to push.
@@ -703,6 +708,7 @@ enum ovs_nat_attr {
* enum ovs_action_attr - Action types.
*
* @OVS_ACTION_ATTR_OUTPUT: Output packet to port.
+ * @OVS_ACTION_ATTR_TRUNC: Output packet to port with truncated packet size.
* @OVS_ACTION_ATTR_USERSPACE: Send packet to userspace according to nested
* %OVS_USERSPACE_ATTR_* attributes.
* @OVS_ACTION_ATTR_SET: Replaces the contents of an existing header. The
@@ -756,6 +762,7 @@ enum ovs_action_attr {
* The data must be zero for the unmasked
* bits. */
OVS_ACTION_ATTR_CT, /* Nested OVS_CT_ATTR_* . */
+ OVS_ACTION_ATTR_TRUNC, /* u16 struct ovs_action_trunc. */
__OVS_ACTION_ATTR_MAX, /* Nothing past this will be accepted
* from userspace. */
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 9a3eb7a..889b78b 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -750,6 +750,10 @@ static void do_output(struct datapath *dp, struct sk_buff
*skb, int out_port,
if (likely(vport)) {
u16 mru = OVS_CB(skb)->mru;
+ u16 cutlen = OVS_CB(skb)->cutlen;
+
+ if (cutlen > 0)
+ pskb_trim(skb, skb->len - cutlen);
if (likely(!mru || (skb->len <= mru + ETH_HLEN))) {
ovs_vport_send(vport, skb);
@@ -858,10 +862,19 @@ static int sample(struct datapath *dp, struct sk_buff
*skb,
return 0;
/* The only known usage of sample action is having a single user-space
+ * action, or having a truncate action followed by a single user-space
* action. Treat this usage as a special case.
* The output_userspace() should clone the skb to be sent to the
* user space. This skb will be consumed by its caller.
*/
+ if (unlikely(nla_type(a) == OVS_ACTION_ATTR_TRUNC)) {
+ struct ovs_action_trunc *trunc = nla_data(a);
+
+ OVS_CB(skb)->cutlen = skb->len > trunc->max_len ?
+ skb->len - trunc->max_len : 0;
+ a = nla_next(a, &rem);
+ }
+
if (likely(nla_type(a) == OVS_ACTION_ATTR_USERSPACE &&
nla_is_last(a, rem)))
return output_userspace(dp, skb, key, a, actions, actions_len);
@@ -1044,13 +1057,18 @@ static int do_execute_actions(struct datapath *dp,
struct sk_buff *skb,
for (a = attr, rem = len; rem > 0;
a = nla_next(a, &rem)) {
int err = 0;
+ int cutlen = OVS_CB(skb)->cutlen;
if (unlikely(prev_port != -1)) {
struct sk_buff *out_skb = skb_clone(skb, GFP_ATOMIC);
- if (out_skb)
+ if (out_skb) {
+ /* skb_clone does not clone the CB. */
+ OVS_CB(out_skb)->cutlen = cutlen;
do_output(dp, out_skb, prev_port, key);
+ }
+ OVS_CB(skb)->cutlen = 0;
prev_port = -1;
}
@@ -1059,6 +1077,14 @@ static int do_execute_actions(struct datapath *dp,
struct sk_buff *skb,
prev_port = nla_get_u32(a);
break;
+ case OVS_ACTION_ATTR_TRUNC: {
+ struct ovs_action_trunc *trunc = nla_data(a);
+
+ OVS_CB(skb)->cutlen = skb->len > trunc->max_len ?
+ skb->len - trunc->max_len : 0;
+ break;
+ }
+
case OVS_ACTION_ATTR_USERSPACE:
output_userspace(dp, skb, key, a, attr, len);
break;
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 856bd8d..fb3e5a3 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -425,6 +425,7 @@ static int queue_userspace_packet(struct datapath *dp,
struct sk_buff *skb,
size_t len;
unsigned int hlen;
int err, dp_ifindex;
+ int cutlen = OVS_CB(skb)->cutlen;
dp_ifindex = get_dpifindex(dp);
if (!dp_ifindex)
@@ -461,6 +462,9 @@ static int queue_userspace_packet(struct datapath *dp,
struct sk_buff *skb,
else
hlen = skb->len;
+ if (cutlen > 0)
+ hlen -= cutlen;
+
len = upcall_msg_size(upcall_info, hlen);
user_skb = genlmsg_new(len, GFP_ATOMIC);
if (!user_skb) {
@@ -515,9 +519,9 @@ static int queue_userspace_packet(struct datapath *dp,
struct sk_buff *skb,
err = -ENOBUFS;
goto out;
}
- nla->nla_len = nla_attr_size(skb->len);
+ nla->nla_len = nla_attr_size(skb->len - cutlen);
- err = skb_zerocopy(user_skb, skb, skb->len, hlen);
+ err = skb_zerocopy(user_skb, skb, skb->len - cutlen, hlen);
if (err)
goto out;
@@ -531,6 +535,7 @@ static int queue_userspace_packet(struct datapath *dp,
struct sk_buff *skb,
out:
if (err)
skb_tx_error(skb);
+ OVS_CB(skb)->cutlen = 0;
kfree_skb(user_skb);
kfree_skb(nskb);
return err;
diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h
index 427e39a..fcb1d51 100644
--- a/net/openvswitch/datapath.h
+++ b/net/openvswitch/datapath.h
@@ -100,11 +100,13 @@ struct datapath {
* @input_vport: The original vport packet came in on. This value is cached
* when a packet is received by OVS.
* @mru: The maximum received fragement size; 0 if the packet is not
+ * @cutlen: The number of bytes from the packet end to be removed.
* fragmented.
*/
struct ovs_skb_cb {
struct vport *input_vport;
u16 mru;
+ u16 cutlen;
};
#define OVS_CB(skb) ((struct ovs_skb_cb *)(skb)->cb)
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index 0bb650f..7bc5405 100644
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -2229,6 +2229,7 @@ static int __ovs_nla_copy_actions(struct net *net, const
struct nlattr *attr,
[OVS_ACTION_ATTR_SAMPLE] = (u32)-1,
[OVS_ACTION_ATTR_HASH] = sizeof(struct ovs_action_hash),
[OVS_ACTION_ATTR_CT] = (u32)-1,
+ [OVS_ACTION_ATTR_TRUNC] = sizeof(struct
ovs_action_trunc),
};
const struct ovs_action_push_vlan *vlan;
int type = nla_type(a);
@@ -2255,6 +2256,14 @@ static int __ovs_nla_copy_actions(struct net *net, const
struct nlattr *attr,
return -EINVAL;
break;
+ case OVS_ACTION_ATTR_TRUNC: {
+ const struct ovs_action_trunc *trunc = nla_data(a);
+
+ if (trunc->max_len < ETH_MIN_FRAME_LEN)
+ return -EINVAL;
+ break;
+ }
+
case OVS_ACTION_ATTR_HASH: {
const struct ovs_action_hash *act_hash = nla_data(a);
diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
index 31cbc8c..6b21fd0 100644
--- a/net/openvswitch/vport.c
+++ b/net/openvswitch/vport.c
@@ -444,6 +444,7 @@ int ovs_vport_receive(struct vport *vport, struct sk_buff
*skb,
OVS_CB(skb)->input_vport = vport;
OVS_CB(skb)->mru = 0;
+ OVS_CB(skb)->cutlen = 0;
if (unlikely(dev_net(skb->dev) != ovs_dp_get_net(vport->dp))) {
u32 mark;
--
2.5.0
